1. Field of the Invention
The invention relates to a management method and management apparatus and is suited for use in, for example, a management apparatus for managing the performance of a storage apparatus in a computer system.
2. Description of Related Art
A hierarchical pool configuration technique for creating a pool by using multiple types of storage devices with different levels of performance has been suggested as a storage virtualization technique (see, for example, Japanese Patent Laid-Open (Kokai) Application Publication No. 2007-066259). The hierarchical pool configuration technique partitions storage areas of virtual volumes into specified size called “pages” and switches, on a page basis according to the I/O quantity per unit time, storage devices to which pages are regularly placed, for example, to high-performance storage devices for pages with high I/O load or to low-performance storage devices for pages with low I/O load.
As compared to a case where storage areas are allocated from a single type of storage devices to virtual volumes, the above-described hierarchical pool configuration technique determines storage devices to be allocated for each minute piece of data called “page.” Therefore, when designing the configuration that satisfies performance requirements and capacity requirements for a system, the capacity of required high-performance storage devices will be reduced and storage costs can be reduced.
Regarding the hierarchical pool configuration technique, storage devices constituting a pool have performance threshold and capacity threshold values. The performance threshold is a value indicating that “if the I/O quantity per unit time exceeds this value, response performance can no longer be guaranteed.” If the sum of I/O quantities per unit time of storage areas allocated by storage devices to virtual volumes exceeds the performance threshold, placement of the storage areas from the relevant storage devices is stopped and the storage areas are placed from storage devices whose level of performance is one level lower than the above-mentioned storage devices. The capacity threshold is a value indicating that if an actual capacity usage rate has reached this value, placement of storage areas from the relevant storage devices to virtual volumes is stopped.
Consequently, it is possible to secure a certain or higher level of response performance of each storage device by setting the performance threshold to the storage devices in the hierarchical pool configuration as described above. It is also possible to not allocate storage areas, which exceed the capacity of the storage devices, to the virtual volumes by setting the capacity threshold to the storage devices.
In a case where the performance of storage devices exceeds the performance threshold in the hierarchical pool configuration, it can be estimated that the relevant storage devices allocate storage areas to one or more pages with a large I/O quantity in virtual volumes, and high load is imposed on the storage devices.
In such a case, pages of the high-performance storage devices cannot be fully utilized, thereby causing a problem of worsening average response performance of the entire system.